1. Field of the Invention
The invention relates to printing machines, and more particularly to an apparatus for the axial guidance and adjustment of a plate cylinder in a rotary printing machine.
2. Description of the Related Art
In a color print, the color images to be printed one after another have to be printed in register with one another. For this purpose, in rotary printing machines the plate cylinder can be adjusted with respect to the lateral, circumferential and, if necessary, diagonal register, apart from solutions in which the printing plate is adjusted directly. For the purpose of adjusting the lateral register, the plate cylinder is shifted in the axial direction. In this context, DE 34 09 194 A 1 describes an apparatus in which the axial movement is produced by means of a threaded spindle driven by a motor. The threaded spindle is connected to the journal of the plate cylinder via ball bearings.
This apparatus is complicated in design and is thus expensive with regard to the manufacturing costs. Furthermore, mechanical parts are affected by play and are subject to wear which increases the play. The play impairs the axial fixing of the cylinder and hence the constancy of register. In addition, during the adjustment of the cylinder position, hysteresis deviations which influence the register occur.
It is therefor an object of the invention to provide an apparatus which is constructed from simple means and which accurately guides and adjusts the cylinder axially.
According to the invention, the apparatus can be set up cost-effectively and such that it renders mechanical gear mechanisms for lateral register adjustment superfluous. It permits the cylinder to be guided without contact and, as a result, without wear and hysteresis, by means of mechanical drives. In an advantageous embodiment of the invention, through direct measurement of the actual position of the cylinder, the associated influence of hysteresis is also dispensed with. As a result, the cylinder is axially positioned and adjusted very accurately overall, which means that a high register accuracy and thus good print quality can be achieved.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.